find  Find files under the given directory tree, recursively    - find files by extension  find root_path -name '*.py'    - find files matching path pattern  find root_path -path '**/lib/**/*.py'    - run a command for each file, use {} within the command to access the filename  find root_path -name '*.py' -exec wc -l {} \;    - find files modified since a certain time  find root_path -name '*.py' -mtime -1d    - find files using case insensitive name matching, of a certain size  find root_path -size +500k -size -10MB -iname '*.TaR.gZ'    - delete files by name, older than a certain number of days  find root_path -name '*.py' -mtime -180d -delete

gcc  Preprocesses and compiles C and C++ source files, then assembles and links them together.    - Compile multiple source files into executable  gcc source1.c source2.c -o executable    - Allow warnings, debug symbols in output  gcc source.c -Wall -Og -o executable    - Include libraries from a different path  gcc source.c -o executable -Iheader_path -Llibrary_path -llibrary_name

git …

1. git add

   git add  Adds changed files to the index    - Add a file to the index  git add PATHSPEC    - Add all files (tracked and untracked)  git add .    - Only add already tracked files  git add -u    - Also add ignored files  git add -f

2. git blame

   git blame  Show commit hash and last author on each line of a file    - Print file with author name and commit hash on each line  git blame file    - Print file with author email and commit hash on each line  git blame -e file

3. git branch

   Main command for working with branches    - List local branches. The current branch is highlighted by *.  git branch    - List all local and remote branches  git branch -a    - Create new branch based on current branch  git branch BRANCH-NAME    - Delete a local branch  git branch -d BRANCH-NAME    - Move/Rename a branch  git branch -mch

4. git checkout

   git checkout  Checkout a branch or paths to the working tree    - Switch to another branch  git checkout BRANCH-NAME    - Create and switch to a new branch  git checkout -b BRANCH-NAME    - Undo unstaged local modification  git checkout .

5. git clone

   git clone  Clone an existing repository    - Clone an existing repository  git clone REMOTE-REPOSITORY-LOCATION    - For cloning from the local machine  git clone -l    - Do it quietly  git clone -q    - Clone an existing repository, and truncate to the specified number of revisions, save your time mostly  git clone --depth 10 REMOTE-REPOSITORY-LOCATION

6. git commit

   git commit  Commit staged files to the repository    - Commit staged files to the repository with comment  git commit -m MESSAGE    - Replace the last commit with currently staged changes  git commit --amend

7. git config

   git config  Get and set repository or global options    - Print list of options for current repository  git config --list --local    - Print global list of options, set in ~/.gitconfig  git config --list --global    - Get full list of options  git config --list    - Get value of alias.ls option  git config alias.st    - Set option alias.ls=status in file ~/.gitconfig  git config --global alias.ls "status"    - Remove option alias.st from ~/.gitconfig  git config --global --unset alias.st

8. git diff

   git diff  Show changes to tracked files    - Show changes to tracked files  git diff PATHSPEC    - Show only names of changed files.  git diff --name-only PATHSPEC    - Output a condensed summary of extended header information.  git diff --summary PATHSPEC

9. git init

   git init  Initializes a new local Git repository    - Initialize a new local repository  git init    - Initialize a barebones repository  git init --bare

10. git log

    git log  Show a history of commits    - Show a history of commits  git log    - Show the history of a particular file or directory, including differences  git log -p path    - Show only the first line of each commits  git log --oneline

11. git merge

    git merge  Merge branches    - Merge a branch with your current branch  git merge BRANCH-NAME    - Edit the merge message  git merge -e BRANCH-NAME

12. git mv

    git mv  Move or rename files and update the git index.    - Move file inside the repo and add the movement to the next commit  git mv path/to/file new/path/to/file    - Rename file and add renaming to the next commit  git mv filename new_filename    - Overwrite the file in the target path if it exists  git mv --force file target

13. git pull

    git pull  Fetch branch from a remote repository and merge it to local repository    - Download changes from default remote repository and merge it  git pull    - Download changes from default remote repository and use fast forward  git pull --rebase    - Download changes from given remote repository and branch, then merge them into HEAD  git pull remote_name branch

14. git push

    git push  Push commits to a remote repository    - Publish local changes on a remote branch  git push REMOTE-NAME LOCAL-BRANCH    - Publish local changes on a remote branch of different name  git push REMOTE-NAME LOCAL-BRANCH:REMOTE-BRANCH    - Remove remote branch  git push REMOTE-NAME :REMOTE-BRANCH    - Remove remote branches which don't exist locally  git push --prune REMOTE-NAME    - Publish tags  git push --tags

15. git remote

    git remote  ge set of tracked repositories (“remotes”)    - Show a list of existing remotes, their names and URL  git remote -v    - Add a remote  git remote add remote_name remote_url    - Change the URL of a remote  git remote set-url remote_name new_url    - Remove a remote  git remote remove remote_name    - Rename a remote  git remote rename old_name new_name

16. git stash

    git stash  Stash local Git changes in a temporary area    - stash current changes (except new files)  git stash save optional_stash_name    - include new files in the stash (leaves the index completely clean)  git stash save -u optional_stash_name    - list all stashes  git stash list    - re-apply the latest stash  git stash pop    - re-apply a stash by name  git stash apply stash_name    - drop a stash by an index  git stash drop stash@{index}

17. git tag

    git tag  Create, list, delete or verify tags.  Tag is reference to specific commit.    - List all tags  git tag    - Create a tag with the given name pointing to the current commit  git tag tag_name    - Create a tag with the given message  git tag tag_name -m tag_message    - Delete the tag with the given name  git tag -d tag_name

grep

grep  Matches patterns in input text  Supports simple patterns and regular expressions    - search for an exact string  grep something file_path    - search recursively in current directory for an exact string  grep -r something .    - use a regex  grep -e ^regex$ file_path    - see 3 lines of context  grep -C 3 something file_path    - print the count of matches instead of the matching text  grep -c something file_path    - use the standard input instead of a file  cat file_path | grep something    - invert match for excluding specific strings  grep -v something

gzip  Compress/uncompress files with gzip compression (LZ77)    - compress a file, replacing it with a gzipped compressed version  gzip file.ext    - decompress a file, replacing it with the original uncompressed version  gzip -d file.ext.gz    - compress a file specifying the output filename  gzip -c file.ext > compressed-file.ext.gz    - uncompress a gzipped file specifying the output filename  gzip -c -d file.ext.gz > uncompressed-file.ext    - specify the compression level. 1=Fastest (Worst), 9=Slowest (Best), Default level is 6  gzip -9 -c file.ext > compressed-file.ext.gz

iconv  Converts text from one encoding to another    - convert file and print to stdout  iconv -f from_encoding -t to_encoding input_file    - convert file to current locale  iconv -f from_encoding input_file > output_file    - list supported encodings  iconv -l

ifconfig  ifconfig - Interface Configurator, used to configure network interfaces.    - View network settings of an ethernet adapter.  ifconfig eth0    - Display details of all interfaces, including disabled interfaces.  ifconfig -a    - Disable eth0 interface.  ifconfig eth0 down    - Enable eth0 interface.  ifconfig eth0 up    - Assign IP address to eth0 interface.  ifconfig eth0 ip_address

kill  Sends a signal to a process  Mostly used for stopping processes    - kill the process  kill process_id    - list signal names  kill -l

less  Opens a file for reading  Allows movement and search  Doesn't read the entire file (suitable for logs)    - open a file  less source_file        - page up / down  d (next), D (previous)        - go to start / end of file  g (start), G (end)        - search for a string  /something   then   n (next), N (previous)        - exit      q

ln  Creates links to files and folders    - create a symbolic link to a file or folder  ln -s path/to/original/file path/to/link    - overwrite a symbolic link to a file  ln -sf path/to/new/original/file path/to/file/link    - overwrite a symbolic link to a folder  ln -sfT path/to/new/original/file path/to/folder/link    - create a hard link to a file or folder  ln path/to/original/file path/to/link

locate  find filenames quickly  - Look for pattern in the database. Note: the database is recomputed periodically (usually weekly or daily).  locate pattern    - Recompute the database. You need to do it if you want to find recently added files.  sudo updatedb

ls  List directory contents    - List all files, even hidden  ls -a    - List all file names (no extra info)  ls -A1    - List all files with their rights, groups, owner  ls -l    - List all files and display the file size in a human readable format  ls -lh    - List all files with a prefix/suffix  ls *suffix    - Sort the results by size, last modified date, or creation date  ls -U    - Reverse the order of the results  ls -r

md5sum  Calculate MD5 cryptographic checksums    - Read a file of MD5SUMs and verify all files have matching checksums  md5sum -c filename.md5

mkdir  Creates a directory    - creates a directory in current folder or given path  mkdir directory    - creates directories recursively (useful for creating nested dirs)      mkdir -p path

more  Opens a file for reading.  Allows movement and search in forward direction only.  Doesn't read the entire file (suitable for logs)    - open a file  more source_file    - page down  d (next)    - search for a string  /something   then   n (next)    - exit  q

mount  Provides access to an entire filesystem in one directory.    - Show all mounted filesystems  mount    - Mount a device  mount -t filesystem_type path_to_device_file directory_to_mount_to    - Mount a CD-ROM device (with the filetype ISO9660) to /cdrom (readonly)  mount -t iso9660 -o ro /dev/cdrom /cdrom    - Mount all the filesystem defined in /etc/fstab  mount -a    - Mount a specific filesystem described in /etc/fstab (e.g. "/dev/sda1 /my_drive ext2 defaults 0 2")  mount /my_drive

mv  Move or rename files and directories    - Move files in abitrary locations  mv source target    - Do not prompt for confirmation before overwriting existing files  mv -f source target    - Do not prompt for confirmation before overwriting existing files but write to standard error before overriding  mv -fi source target    - Move files in verbose mode, showing files after they are moved  mv -v source target

mysql  the MySQL command-line tool    - Connect to a database  mysql database_name    - Connect to a database using credentials  mysql -u user -ppassword database_name    - Execute SQL statements in a script file (batch file)  mysql database_name < script.sql

nc  reads and writes tcp or udp data    - listen on a specified port  nc  -l port    - connect to a certain port (you can then write to this port)  nc ip_address port    - set a timeout  nc -w timeout_in_seconds ipaddress port    - serve a file  cat somefile.txt | nc -l port    - receive a file  nc ip_address port > somefile.txt    - server stay up after client detach  nc -k -l port    - client stay up after EOF  nc -q timeout ip_address

passwd  passwd is a tool used to change a user's password.    - Change the password of the current user  passwd new password    - Change the password of the specified user  passwd username new password    - Get the current statuts of the user  passwd -S    - Make the password of the account blank (it will set the named account passwordless)  passwd -d

ping  send ICMP ECHO_REQUEST packets to network hosts    - Ping host  ping host    - Ping host limiting the number of packages to be send to four  ping -c 4 host    - Ping host, waiting for 0.5 s between each request (default is 1 s)  ping -i 0.5 host    - Ping host without trying to lookup symbolic names for addresses  ping -n host

pip  Python package manager    - Install a package  pip install package_name    - Install a specific version of a package  pip install package_name==package_version    - Upgrade a package  pip install -U package_name    - Uninstall a package  pip uninstall package_name    - Save installed packages to file  pip freeze > requirements.txt    - Install packages from file  pip install -r requirements.txt

pwd  Print name of current/working directory    - Print the current directory  pwd    - Print the current directory, and resolve all symlinks (e.g. show the "physical" path)  pwd -P

rename  renames multiple files    - Change foo to bar in matching filenames  rename 's/foo/bar/' *.txt    - Convert to lower case  rename -c *.txt    - No action, just show what renames would occur  rename -n 's/foo/bar/' *.txt

rm  Remove files or directories    - Remove files from arbitrary locations  rm /path/to/file /otherpath/to/file2    - Remove recursively a directory and all it's subdirectories  rm -r /path/to/folder    - Prompt before every removal  rm -i \*

scp  Copies files between hosts on a network  Works over a secure connection (SSH)    - upload a file, or upload and rename a file  scp /local/file.txt 10.0.0.1:/remote/path/newname.txt    - download a file  scp 10.0.0.1:/remote/path/file.txt /local/folder    - upload or download a directory  scp -r 10.0.0.1:/remote/path /local/folder    - specify username on host  scp /local/file.txt my_user@10.0.0.1:/remote/path    - copy a file from one host to another  scp 10.0.0.1:/remote/path/file.txt 20.0.0.2:/other/remote/path    - download a file with ssh key  scp -i /local/key 10.0.0.1:/remote/path/file.txt /local/folder

screen  Hold a session open on a remote server. Manage multiple windows with a single SSH connection.    - Start a new screen session  screen    - Start a new named screen session  screen -S name    - Show open screen sessions  screen -ls    - Reattach to an open screen  screen -r screen id    - Detach from inside a screen  ctrl+A D    - Kill a detached screen  screen -X -S screen id quit

sed  Run replacements based on regular expressions    - replace all occurrences of a string in a file, and print the result  sed 's/find/replace/g' filename    - replace all occurrences of a string in a file, and overwrite the file  contents  sed -i 's/find/replace/g' filename    - replace all occurrences of an extended regular expression in a file  sed -E 's/regex/replace/g' filename    - replace all occurrences of multiple strings in a file  sed -e 's/find/replace/g' -e 's/find/replace/g' filename

shutdown  Shutdown and reboot the system    - Power off (halt) immediately  shutdown -h now    - Reboot immediately  shutdown -r now    - Reboot in 5 minutes  shutdown -r +5 &    - Cancel a pending shutdown/reboot operation  shutdown -c

SSH  Secure Shell is a protocol used to securely log onto remote systems.  It can be used for logging or executing commands on a remote server.    - connecting to a remote server  ssh username@remote_host    - connecting to a remote server with a specific identity (private key)  ssh -i /path/to/key_file username@remote_host    - connecting to a remote server with specific port  ssh username@remote_host -p 2222    - run a command on a remote server  ssh remote_host "command -with -flags"    - ssh tunneling: dynamic port forwarding (SOCKS proxy on localhost:9999)  ssh -D 9999 -C username@remote_host    - ssh tunneling: forward a specific port (localhost:9999 to slashdot.org:80)  ssh -L 9999:slashdot.org:80 username@remote_host    - ssh enable agent forward  ssh -A username@remote_host

SSHFS  filesystem client based on ssh    - mounting remote directory  sshfs username@remote_host:remote_directory mountpoint    - unmounting remote directory  fusermount -u mountpoint    - mounting remote directory from server with specific port  sshfs username@remote_host:remote_directory -p 2222    - use compression  sshfs username@remote_host:remote_directory -C

strace  Troubleshooting tool for tracing system calls    - Start tracing a specific process by its PID  strace -p pid    - Trace a process and filter output by system call  strace -p pid -e system call name    - Count time, calls, and errors for each system call and report a summary on program exit.  strace -p pid -c

sudo  execute a command as another user    - Listing of an unreadable directory:  sudo ls /usr/local/scrt    - To edit a file as user www:  sudo -u www vi /var/www/index.html    - To shutdown the machine:  sudo shutdown -r +10 "Cya soon!"    - To repeat the last command as sudo  sudo !!

svn  Subversion command line client tool    - Check out a working copy from a repository  svn co url/to/repository    - Bring changes from the repository into the working copy  svn up    - Put files and directories under version control, scheduling them for addition to repository. They will be added in next commit.  svn add PATH...    - Send changes from your working copy to the repository  svn ci -m commit log message [PATH...]    - Show detailed help  svn help

tail  Display the last part of a file    - show last 'num' lines in file  tail -n num file    - show all file since line 'num'  tail -n +num file    - show last 'num' bytes in file  tail -c num file    - keep reading file until ctrl-c  tail -f file

tar  Archiving utility  Optional compression with gzip / bzip    - create an archive from files  tar cf target.tar file1 file2 file3    - create a gzipped archive  tar czf target.tar.gz file1 file2 file3    - extract an archive in a target folder  tar xf source.tar -C folder    - extract a gzipped archive in the current directory  tar xzf source.tar.gz    - extract a bzipped archive in the current directory  tar xjf source.tar.bz2    - create a compressed archive, using archive suffix to determine the compression program  tar caf target.tar.xz file1 file2 file3    - list the contents of a tar file  tar tvf source.tar

tcpdump  Dump traffic on a network    - capture the traffic of a specific interface  tcpdump -i eth0    - capture all TCP traffic showing contents (ASCII) in console  tcpdump -A tcp    - capture the traffic from or to a host  tcpdump host www.example.com    - capture the traffic from a specific interface, source, destination and port  tcpdump -i eth0 src 192.168.1.1 dest 192.168.1.2 and port 80    - capture the traffic of a network  tcpdump net 192.168.1.0/24    - capture all traffic except traffic over port 22 and save to a dump file  tcpdump -w dumpfile.pcap not port 22

telnet  telnet is used to connect to a specified port of a host    - telnet to a certain port  telnet  ip_address port    - to exit a telnet session  quit    - default escape character  CTRL + ]    - specify an escape character (x is the escape character)  telnet -e x ip_address port

top  Display dynamic real-time information about running processes.    - Start top  top    - Start top ignoring any idle or zombie processes  top -i    - Start top displaying only processes owned by given user  top -u user-name    - Get help about interactive commands  ?

touch  Change a file access and modification times (atime, mtime)    - Create a new empty file(s) or change the times for existing file(s) to current time.`  touch filename    - Set the times on a file to match those on second file  touch -r filename2 filename

tree  Show the contents of the current directory as a tree.    - Show files and directories with a depth of 'num'  tree -L num    - Show directories only  tree -d    - Show hidden files too  tree -a    - Print human readable size of files  tree -h    - Print the full path for each file  tree -f    - Print the tree without lines and indentation. Useful when used with -f  tree -i

umount  Revokes access to an entire filesystem mounted to a directory.  A filesystem cannot be unmounted when it is busy.    - Unmount a filesystem  umount path_to_device_file    - OR  umount path_to_mounted_directory    - Unmount all mounted filesystems (dangerous!)  umount -a

uname  Print details about the current machine and the operating system running on it.  Note: If you're on Linux, try also the lsb_release command.    - Print hardware-related information: machine and processor  uname -mp    - Print software-related information: operating system, release number, and version  uname -srv    - Print the nodename (hostname) of the system  uname -n    - Print all available system information (hardware, software, nodename)  uname -a

unzip  Extract compressed files in a ZIP archive    - extract zip file(s) (for multiple files, seperate file paths by spaces)  unzip file(s)    - extract zip files(s) to given path  unzip files(s) -d /path/to/put/extracted/files    - list the contents of a zip file without extracting  unzip -l file

wget  Download files from the Web  Supports HTTP, HTTPS, and FTP    - Download a URL to a file  wget -O filename "url"    - Limit download speed  wget --limit-rate=200k url    - Continue an incomplete download  wget -c url    - Download a full website  wget --mirror -p --convert-links -P target_folder url    - FTP download with username and password  wget --ftp-user=username --ftp-password=password url

xargs  execute a command with piped arguments    - main use  arguments | xargs command    - handling whitespace in arguments  arguments_null_terminated | xargs -0 command    - example: list unneeded packages with deborphan and remove them with apt-get  sudo deborphan | xargs sudo apt-get remove